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.\" ========================================================================
.\"
.IX Title "PT-CONFIG-DIFF 1p"
.TH PT-CONFIG-DIFF 1p "2012-06-15" "perl v5.14.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
pt\-config\-diff \- Diff MySQL configuration files and server variables.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
Usage: pt-config-diff [\s-1OPTION\s0...] \s-1CONFIG\s0 \s-1CONFIG\s0 [\s-1CONFIG\s0...]
.PP
pt-config-diff diffs MySQL configuration files and server variables.
\&\s-1CONFIG\s0 can be a filename or a \s-1DSN\s0.  At least two \s-1CONFIG\s0 sources must be given.
Like standard Unix diff, there is no output if there are no differences.
.PP
Diff host1 config from \s-1SHOW\s0 \s-1VARIABLES\s0 against host2:
.PP
.Vb 1
\&  pt\-config\-diff h=host1 h=host2
.Ve
.PP
Diff config from [mysqld] section in my.cnf against host1 config:
.PP
.Vb 1
\&  pt\-config\-diff /etc/my.cnf h=host1
.Ve
.PP
Diff the [mysqld] section of two option files:
.PP
.Vb 1
\&   pt\-config\-diff /etc/my\-small.cnf /etc/my\-large.cnf
.Ve
.SH "RISKS"
.IX Header "RISKS"
The following section is included to inform users about the potential risks,
whether known or unknown, of using this tool.  The two main categories of risks
are those created by the nature of the tool (e.g. read-only tools vs. read-write
tools) and those created by bugs.
.PP
pt-config-diff reads MySQL's configuration and examines it and is thus very
low risk.
.PP
At the time of this release there are no known bugs that pose a serious risk.
.PP
The authoritative source for updated information is always the online issue
tracking system.  Issues that affect this tool will be marked as such.  You can
see a list of such issues at the following \s-1URL:\s0
http://www.percona.com/bugs/pt\-config\-diff <http://www.percona.com/bugs/pt-config-diff>.
.PP
See also \*(L"\s-1BUGS\s0\*(R" for more information on filing bugs and getting help.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
pt-config-diff diffs MySQL configurations by examining the values of server
system variables from two or more \s-1CONFIG\s0 sources specified on the command
line.  A \s-1CONFIG\s0 source can be a \s-1DSN\s0 or a filename containing the output of
\&\f(CW\*(C`mysqld \-\-help \-\-verbose\*(C'\fR, \f(CW\*(C`my_print_defaults\*(C'\fR, \f(CW\*(C`SHOW VARIABLES\*(C'\fR, or
an option file (e.g. my.cnf).
.PP
For each \s-1DSN\s0 \s-1CONFIG\s0, pt-config-diff connects to MySQL and gets variables
and values by executing \f(CW\*(C`SHOW /*!40103 GLOBAL*/ VARIABLES\*(C'\fR.  This is
an \*(L"active config\*(R" because it shows what server values MySQL is
actively (currently) running with.
.PP
Only variables that all \s-1CONFIG\s0 sources have are compared because if a
variable is not present then we cannot know or safely guess its value.
For example, if you compare an option file (e.g. my.cnf) to an active config
(i.e. \s-1SHOW\s0 \s-1VARIABLES\s0 from a \s-1DSN\s0 \s-1CONFIG\s0), the option file will probably
only have a few variables, whereas the active config has every variable.
Only values of the variables present in both configs are compared.
.PP
Option file and \s-1DSN\s0 configs provide the best results.
.SH "OUTPUT"
.IX Header "OUTPUT"
There is no output when there are no differences.  When there are differences,
pt-config-diff prints a report to \s-1STDOUT\s0 that looks similar to the following:
.PP
.Vb 5
\&  2 config differences
\&  Variable                  my.master.cnf   my.slave.cnf
\&  ========================= =============== ===============
\&  datadir                   /tmp/12345/data /tmp/12346/data
\&  port                      12345           12346
.Ve
.PP
Comparing MySQL variables is difficult because there are many variations and
subtleties across the many versions and distributions of MySQL.  When a
comparison fails, the tool prints a warning to \s-1STDERR\s0, such as the following:
.PP
.Vb 3
\&  Comparing log_error values (mysqld.log, /tmp/12345/data/mysqld.log)
\&  caused an error: Argument "/tmp/12345/data/mysqld.log" isn\*(Aqt numeric
\&  in numeric eq (==) at ./pt\-config\-diff line 2311.
.Ve
.PP
Please report these warnings so the comparison functions can be improved.
.SH "EXIT STATUS"
.IX Header "EXIT STATUS"
pt-config-diff exits with a zero exit status when there are no differences, and
1 if there are.
.SH "OPTIONS"
.IX Header "OPTIONS"
This tool accepts additional command-line arguments.  Refer to the
\&\*(L"\s-1SYNOPSIS\s0\*(R" and usage information for details.
.IP "\-\-ask\-pass" 4
.IX Item "--ask-pass"
Prompt for a password when connecting to MySQL.
.IP "\-\-charset" 4
.IX Item "--charset"
short form: \-A; type: string
.Sp
Default character set.  If the value is utf8, sets Perl's binmode on
\&\s-1STDOUT\s0 to utf8, passes the mysql_enable_utf8 option to DBD::mysql, and
runs \s-1SET\s0 \s-1NAMES\s0 \s-1UTF8\s0 after connecting to MySQL.  Any other value sets
binmode on \s-1STDOUT\s0 without the utf8 layer, and runs \s-1SET\s0 \s-1NAMES\s0 after
connecting to MySQL.
.IP "\-\-config" 4
.IX Item "--config"
type: Array
.Sp
Read this comma-separated list of config files; if specified, this must be the
first option on the command line.  (This option does not specify a \s-1CONFIG\s0;
it's equivalent to \f(CW\*(C`\-\-defaults\-file\*(C'\fR.)
.IP "\-\-daemonize" 4
.IX Item "--daemonize"
Fork to the background and detach from the shell.  \s-1POSIX\s0
operating systems only.
.IP "\-\-defaults\-file" 4
.IX Item "--defaults-file"
short form: \-F; type: string
.Sp
Only read mysql options from the given file.  You must give an absolute
pathname.
.IP "\-\-help" 4
.IX Item "--help"
Show help and exit.
.IP "\-\-host" 4
.IX Item "--host"
short form: \-h; type: string
.Sp
Connect to host.
.IP "\-\-ignore\-variables" 4
.IX Item "--ignore-variables"
type: array
.Sp
Ignore, do not compare, these variables.
.IP "\-\-password" 4
.IX Item "--password"
short form: \-p; type: string
.Sp
Password to use for connection.
.IP "\-\-pid" 4
.IX Item "--pid"
type: string
.Sp
Create the given \s-1PID\s0 file when daemonized.  The file contains the process
\&\s-1ID\s0 of the daemonized instance.  The \s-1PID\s0 file is removed when the
daemonized instance exits.  The program checks for the existence of the
\&\s-1PID\s0 file when starting; if it exists and the process with the matching \s-1PID\s0
exists, the program exits.
.IP "\-\-port" 4
.IX Item "--port"
short form: \-P; type: int
.Sp
Port number to use for connection.
.IP "\-\-[no]report" 4
.IX Item "--[no]report"
default: yes
.Sp
Print the MySQL config diff report to \s-1STDOUT\s0.  If you just want to check
if the given configs are different or not by examining the tool's exit
status, then specify \f(CW\*(C`\-\-no\-report\*(C'\fR to suppress the report.
.IP "\-\-report\-width" 4
.IX Item "--report-width"
type: int; default: 78
.Sp
Truncate report lines to this many characters.  Since some variable values can
be long, or when comparing multiple configs, it may help to increase the
report width so values are not truncated beyond readability.
.IP "\-\-set\-vars" 4
.IX Item "--set-vars"
type: string; default: wait_timeout=10000
.Sp
Set these MySQL variables.  Immediately after connecting to MySQL, this string
will be appended to \s-1SET\s0 and executed.
.IP "\-\-socket" 4
.IX Item "--socket"
short form: \-S; type: string
.Sp
Socket file to use for connection.
.IP "\-\-user" 4
.IX Item "--user"
short form: \-u; type: string
.Sp
MySQL user if not current user.
.IP "\-\-version" 4
.IX Item "--version"
Show version and exit.
.SH "DSN OPTIONS"
.IX Header "DSN OPTIONS"
These \s-1DSN\s0 options are used to create a \s-1DSN\s0.  Each option is given like
\&\f(CW\*(C`option=value\*(C'\fR.  The options are case-sensitive, so P and p are not the
same option.  There cannot be whitespace before or after the \f(CW\*(C`=\*(C'\fR and
if the value contains whitespace it must be quoted.  \s-1DSN\s0 options are
comma-separated.  See the percona-toolkit manpage for full details.
.IP "\(bu" 4
A
.Sp
dsn: charset; copy: yes
.Sp
Default character set.
.IP "\(bu" 4
D
.Sp
dsn: database; copy: yes
.Sp
Default database.
.IP "\(bu" 4
F
.Sp
dsn: mysql_read_default_file; copy: yes
.Sp
Only read default options from the given file
.IP "\(bu" 4
h
.Sp
dsn: host; copy: yes
.Sp
Connect to host.
.IP "\(bu" 4
p
.Sp
dsn: password; copy: yes
.Sp
Password to use when connecting.
.IP "\(bu" 4
P
.Sp
dsn: port; copy: yes
.Sp
Port number to use for connection.
.IP "\(bu" 4
S
.Sp
dsn: mysql_socket; copy: yes
.Sp
Socket file to use for connection.
.IP "\(bu" 4
u
.Sp
dsn: user; copy: yes
.Sp
User for login if not current user.
.SH "ENVIRONMENT"
.IX Header "ENVIRONMENT"
The environment variable \f(CW\*(C`PTDEBUG\*(C'\fR enables verbose debugging output to \s-1STDERR\s0.
To enable debugging and capture all output to a file, run the tool like:
.PP
.Vb 1
\&   PTDEBUG=1 pt\-config\-diff ... > FILE 2>&1
.Ve
.PP
Be careful: debugging output is voluminous and can generate several megabytes
of output.
.SH "SYSTEM REQUIREMENTS"
.IX Header "SYSTEM REQUIREMENTS"
You need Perl, \s-1DBI\s0, DBD::mysql, and some core packages that ought to be
installed in any reasonably new version of Perl.
.SH "BUGS"
.IX Header "BUGS"
For a list of known bugs, see http://www.percona.com/bugs/pt\-config\-diff <http://www.percona.com/bugs/pt-config-diff>.
.PP
Please report bugs at https://bugs.launchpad.net/percona\-toolkit <https://bugs.launchpad.net/percona-toolkit>.
Include the following information in your bug report:
.IP "\(bu" 4
Complete command-line used to run the tool
.IP "\(bu" 4
Tool \*(L"\-\-version\*(R"
.IP "\(bu" 4
MySQL version of all servers involved
.IP "\(bu" 4
Output from the tool including \s-1STDERR\s0
.IP "\(bu" 4
Input files (log/dump/config files, etc.)
.PP
If possible, include debugging output by running the tool with \f(CW\*(C`PTDEBUG\*(C'\fR;
see \*(L"\s-1ENVIRONMENT\s0\*(R".
.SH "DOWNLOADING"
.IX Header "DOWNLOADING"
Visit http://www.percona.com/software/percona\-toolkit/ <http://www.percona.com/software/percona-toolkit/> to download the
latest release of Percona Toolkit.  Or, get the latest release from the
command line:
.PP
.Vb 1
\&   wget percona.com/get/percona\-toolkit.tar.gz
\&
\&   wget percona.com/get/percona\-toolkit.rpm
\&
\&   wget percona.com/get/percona\-toolkit.deb
.Ve
.PP
You can also get individual tools from the latest release:
.PP
.Vb 1
\&   wget percona.com/get/TOOL
.Ve
.PP
Replace \f(CW\*(C`TOOL\*(C'\fR with the name of any tool.
.SH "AUTHORS"
.IX Header "AUTHORS"
Baron Schwartz and Daniel Nichter
.SH "ABOUT PERCONA TOOLKIT"
.IX Header "ABOUT PERCONA TOOLKIT"
This tool is part of Percona Toolkit, a collection of advanced command-line
tools developed by Percona for MySQL support and consulting.  Percona Toolkit
was forked from two projects in June, 2011: Maatkit and Aspersa.  Those
projects were created by Baron Schwartz and developed primarily by him and
Daniel Nichter, both of whom are employed by Percona.  Visit
<http://www.percona.com/software/> for more software developed by Percona.
.SH "COPYRIGHT, LICENSE, AND WARRANTY"
.IX Header "COPYRIGHT, LICENSE, AND WARRANTY"
This program is copyright 2011\-2012 Percona Inc.
Feedback and improvements are welcome.
.PP
\&\s-1THIS\s0 \s-1PROGRAM\s0 \s-1IS\s0 \s-1PROVIDED\s0 \*(L"\s-1AS\s0 \s-1IS\s0\*(R" \s-1AND\s0 \s-1WITHOUT\s0 \s-1ANY\s0 \s-1EXPRESS\s0 \s-1OR\s0 \s-1IMPLIED\s0
\&\s-1WARRANTIES\s0, \s-1INCLUDING\s0, \s-1WITHOUT\s0 \s-1LIMITATION\s0, \s-1THE\s0 \s-1IMPLIED\s0 \s-1WARRANTIES\s0 \s-1OF\s0
\&\s-1MERCHANTABILITY\s0 \s-1AND\s0 \s-1FITNESS\s0 \s-1FOR\s0 A \s-1PARTICULAR\s0 \s-1PURPOSE\s0.
.PP
This program is free software; you can redistribute it and/or modify it under
the terms of the \s-1GNU\s0 General Public License as published by the Free Software
Foundation, version 2; \s-1OR\s0 the Perl Artistic License.  On \s-1UNIX\s0 and similar
systems, you can issue `man perlgpl' or `man perlartistic' to read these
licenses.
.PP
You should have received a copy of the \s-1GNU\s0 General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, \s-1MA\s0  02111\-1307  \s-1USA\s0.
.SH "VERSION"
.IX Header "VERSION"
pt-config-diff 2.1.2